Conventionally, copper wires are widely used for transmitting electrical signals or data between different components in a cheap and convenient way. In a high performance electronic system, since more and more processors are provided and the signal processing speed upgrades, it is important to enhance the quality and speed of transmitting the signals and data between the processors. However, the conventional copper wires fail to meet these requirements.
Compared with the electrical signals, optical signals can be transmitted over longer distances and at higher bandwidths. Therefore, optical connection is much emphasized nowadays, and the optical transmission gradually replaces the electrical transmission. For example, with development of light emitting diodes (LEDs) and semiconductor laser, light becomes suitable to be a transmission medium. An optical coupler device may be used to convert electrical signals into optical signals, convert optical signals into electrical signals, and emit and receive the electrical signals and optical signals. The optical coupler device includes for example an optical emitter or a light source unit for emitting optical signals, an optical receiver or a light-detecting unit for receiving optical signals, or a driver circuit or an amplifier circuit for driving these units or amplifying these signals. The optical emitter and the optical receiver are usually packaged in a coupler module and there is no electrical or physical connection therein. In other words, the electrical interference is eliminated as much as possible for the optical coupler device.
An optical coupler device has been described in U.S. Pat. No. 7,306,378. Please refer to FIG. 1A, a cross-sectional view illustrating the optical coupler device 101. The optical coupler device 101 includes a trench 105 defined in a semiconductor substrate 103. A reflector 107 is defined at a first end of the trench 105, and there is an angle between the reflector 107 and the lengthwise direction of the trench 105. An optical fiber 109 is disposed in the trench 105 at a second end of the trench 105. An optical device 111 is mounted on the semiconductor substrate 103 proximate to the trench 105 such that the optical device 111 is optically coupled to the optical fiber 109 via the reflector 107. The optical device 111 may be an optical emitter for outputting optical signals 113 or an optical receiver for receiving optical signals 113.
The semiconductor substrate 103 is mounted on a printed circuit board (PCB) 115 including contacts 117 which are electrically coupled to the semiconductor substrate 103. A circuit 125 is included in another semiconductor substrate 127 which is mounted on the semiconductor substrate 103 by contacts 131. The circuit 125 can drive or control the optical device 111 to convert electrical signals 119 from the contacts 117 into optical signals 113. The optical signals 113 are reflected by the reflector 107 and outputted through the optical fiber 109. In a reverse direction, the optical signals 113 inputted from the optical fiber 109 are reflected by the reflector 107 and received by the optical device 111. The optical signals 113 are converted into electrical signals 119 to be outputted through the contacts 117. A lid 133 is mounted over the semiconductor substrate 103 and encloses the optical device 111. The lid 133 protects the enclosed items.
A plurality of corresponding optical devices 111, trenches 105 and optical fibers 109 may be included in an optical coupler device 101. As shown in FIG. 1B, two optical coupler devices 101a and 101b, each including a plurality of corresponding optical devices 111, trenches 105 and optical fibers 109, are connected to each other through the representative optical fibers 109a and 109b to achieve signal transmission.
However, it is difficult to dig fine trenches in the semiconductor substrate. It is also difficult to dispose the optical fibers in the fine trenches. A slight error may affect the optical transmission because the light cannot travel in the optical coupler device precisely.
Therefore, there is a need of providing an optical coupler module which can be manufactured easily without complicated assembling and aligning action in order to obviate the drawbacks encountered from the prior art.